Site-Specific 18F Peptide Labeling via Aldehyde Intermediates
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Solution Overview
Problem
Current methods for labeling peptides with 18F are time-consuming and lack site-specificity, resulting in low radiochemical yield and purity, making them unsuitable for rapid and efficient preparation of radiopharmaceuticals for PET imaging.
Innovation Solution
A method involving the reaction of specific compounds with aldehyde or ketone moieties, using oxidizing agents to generate reactive groups, which react site-specifically with ammonia derivatives or hydrazine groups, allowing for the chemoselective introduction of 18F into peptides, thereby forming stable conjugates with improved pharmacokinetics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If active esters of fluorine labelled synthon are used for labelling peptides and proteins with 18F, then labelling can be achieved, but the method is not site-specific and requires time-consuming preparation
Solution Approach 1:
The patent introduces an aldehyde or ketone group as an intermediary functional group on the peptide or protein that reacts specifically with hydroxylamine or aminoxy groups. This intermediary group enables site-specific labelling by creating a unique reaction site that does not compete with other functional groups on the peptide, thereby achieving both ease of manufacture and manufacturing precision
Solution Approach 2:
The patent modifies the peptide or protein at a specific location by introducing an aldehyde or ketone group at a predetermined site. This local modification creates a unique reactive site with distinct chemical properties that differ from other functional groups on the molecule, enabling site-specific 18F labelling while maintaining overall peptide structure and function
2Strength
If multiple amine functions are present on the peptide, then the peptide is more reactive towards labelled synthon, but labelling becomes non-site-specific with multiple equally reactive functions
Solution Approach 1:
The patent uses an aldehyde or ketone group as an intermediary that reacts with hydroxylamine or aminoxy groups to form a specific conjugate. This intermediary reaction pathway is chemoselective and does not compete with other amine functions on the peptide, thereby maintaining high reactivity at the intended site while avoiding non-specific labelling of other amine groups
Solution Approach 2:
The patent changes the chemical parameter of the labelling reaction by using aldehyde/ketone chemistry instead of traditional active ester chemistry. This parameter change creates a new reaction pathway with different selectivity characteristics, allowing site-specific labelling even in the presence of multiple amine functions that would otherwise compete for reaction
3Productivity
If rapid and efficient 18F introduction is achieved, then radiochemical yield improves, but chemoselectivity and site-specificity may be compromised
Solution Approach 1:
The patent introduces the aldehyde or ketone group into the peptide or protein structure in advance, before the 18F labelling step. This preliminary action creates a pre-positioned reactive site that is ready for rapid 18F introduction without requiring complex in-situ generation during the labelling process, thereby achieving both high productivity and chemoselectivity
Solution Approach 2:
The aldehyde or ketone group serves as an intermediary that facilitates rapid 18F introduction through its specific reaction with hydroxylamine or aminoxy groups. This intermediary mechanism is both fast and highly chemoselective, resolving the contradiction between productivity and chemoselectivity by providing a reaction pathway that is simultaneously rapid and specific
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables rapid, chemoselective, and high-yield 18F-labeling of peptides, facilitating the production of radiopharmaceuticals with improved site-specificity and pharmacokinetic properties, suitable for PET imaging and tumor diagnosis.
Implementation Method 1
R1 is an aldehyde moiety, a ketone moiety, a protected aldehyde such as an acetal, a protected ketone, such as a ketal, or a functionality, such as diol or N-terminal serine residue, which can be rapidly and efficiently oxidised to an aldehyde or ketone using an oxidising agent
Implementation Method 2
R2 is a functional group which, under mild conditions such as aqueous buffer, reacts site-specifically with R1 yielding a stable conjugate
Data Source
AI summary
The invention relates to conjugates of formula (V) or (VI): wherein X is —CO—NH—, —NH—, —O—, —NHCONH—, or —NHCSNH—; their use as radiopharmaceuticals, processes for their preparation, and synthetic intermediates used in such processes.